filver to 64°. But to what degree the more imperfect animals are capable of being rendered hotter and colder, at one time than another, I have not been able to determine. The torpidity of these animals in our winter is probably Owing to the great change wrought in their temperature by the external heat and cold. The cold in their bodies is carried to fuch a degree, as in great measure to put a top, while it lafts, to the vital functions. In warmer climates no fuch effect is produced. In this refpect they refemble vegetables.

From the foregoing experiments it appears; firft, that plants when in a state of actual vegetation, or even in fuch a ftate as to be capable of vegetating under certain circumstances, must be deprived of their principle of vegetation before they can be frozen. Secondly, vegetables have a power within themfelves of producing or generating heat; but not always in proportion to the diminution of heat by application of cold, fo as to retain at all times an uniform degree of heat; for the internal temperature of vegetables is fufceptible of variations to a much greater extent indeed than that of the more imperfect animals; but ftill within certain limits. Beyond thefe limits the principle of vegetable, as of animal life, refifts any further change. Thirdly, the heat of vegetables varies, according to the temperature of the medium in which they are, which we difcover by varying that temperature, and obferving the heat of the vegetable. Fourthly, the expence of the vegetating powers in this cafe is proportioned to the neceflity,

It

and the whole vegetable powerk may be exhaufted in this way. Fifthly, this power is moft probably in proportion to the perfection of the plant, the natural heat proper to each fpecies, and the age of each individual. may alfo perhaps depend, in fome degree, on other circumstances not hitherto obferved; for in experiment II. the old fhoot did not lofe its powers, while that which was young or growing did; and in experiment III. and IV. we found, that the young growing shoot of the fir was with great difficulty frozen at 10°, while a bean-leaf was eafily frozen at 22°; and in experiment V. the young fhoot of the fir thawed the ice at 28°, much fafter than the leaf of the bean. Sixthly, it is probably by means of this principle, that vegetables are adapted to different climates. Seventhly, that fufpenfion of the functions of vegetable life, which takes place during the winter feafon, is probably owing to their being fufceptible of fuch a great variation of internal temperature: Eighthly, the roots of vegetables are capable of refifting cold more than the ftem or leaf; therefore, though the ftem be killed by cold, the root may be preserved, as daily experience evinces. The texture of vegetables alters very much by the lofs of life, especially thofe which are watry and young; from being brittle and crifp they become tough and flexible. The leaf of a bean when in full health is thick and maffy, repels water as if greafy, and will often break before it is confiderably bent; but if it is killed flowly by cold, it will lofe all thefe properties, becoming then pliable and flaccid; deprived

af

of its power of repelling water, it is easily made wet, and appears like boiled greens. If killed quickly, by being frozen immediately, it will remain in the fame ftate as when alive; but upon thawing, will immediately lofe all its former texture. This is fo remark able, that it would induce one to believe, that it loft confiderably of its fubftance: but from experiment VI. it is evident that it does not. The fame thing happens to a plant when killed by electricity. If a growing juicy plant receives a ftroke of electricity fufficient to kill it, its leaves droop, and the whole becomes flexible.

So far animal and vegetable life appear to be the fame; yet an animal and a vegetable differ in one very material circumftance, which it may be proper to take particular notice of in this place, as it fhews itself with remarkable evidence in thefe experiments. An animal is equally old in all its parts, excepting where new parts are formed in confequence of diseases; and we find, that thefe new or young parts in animals, like the young hoots of vegetables, are not able to fupport life equally with the old; but every plant has in it a feries of ages. According to its years, it has parts of all the fucceffive ages from its first forma tion; each part having powers equal to its age, and each part, in this refpect, being fimilar to animals of fo many different ages. Youth in all cafes is a state of imperfection; for we find that few animals that come into the world

in winter live, unless they are particularly taken care of; and we may obferve the fame of vegetables. I found that a young plant was more easily killed than an old one; as alfo the youngest part of the fame plant.

This power of generating heat feems to be peculiar to animals and vegetables while alive. It is in both a power only of oppofition and refiftance; for it is not found to exert itself spontaneously and unprovoked; but must always be excited by the energy of fome external frigorific agent. In animals it does not depend on the motion of the blood, as fome have fuppofed, because it belongs to animals who have no circulation; befides, the nose of a dog, which is nearly always of the fame heat in all temperatures of the air, is well fupplied with blood: nor can it be faid to depend upon the nervous fyftem, for it is found in animals that have neither brain or nerves. It is then most probable, that it depends on fome other principle peculiar to both, and which is one of the properties of life; which can, and does, act inde pendently of circulation, fenfation, and volition; viz. that power which preferves and regulates the internal machine, and which appears to be common to animals and vegetables. This principle is in the most perfect state when the body is in health, and in many deviations from that state, we find that its action is extremely uncertain and irregular; fometimes rifing higher than the standard, and at

other

other times falling much below it. Inftances of this we have in different diseases, and even in the fame disease, in very fhort intervals of time. A very remarkable one fell under my own obfervation, in a gentleman who was taken with an apoplectic fit; while he lay infenfible in bed, and covered with blankets, I found that his whole body would, in an inftant, become extremely cold in every part; continue fo for fome time; and, in as fhort a time, he would become extremely hot. While this was going on for feveral hours alternately, there was no fenfible alteration in his pulfe.

pared from them, allowed him a glafs of wine or a little beer occafionally, but chiefly to confine himfelf to water. He purfued the plan very fcrupulously, loft his redundant fat, grew active as ufual in about fix months. I recommended a perfeveranee for a few months longer; then to allow himself light animal food once or twice a week, and gradually to fall into his ufual way of living. He grew well, and continued fo.

A young unmarried woman, about twenty-three years of age, of a low ftature, and very fat, applied to me for affiftance in a great difficulty of breathing, fomnolency, and incapacity for any exercife. It was a hardship to her to be obliged the floor of her apartment. to go up ftairs, and at laft to cross

fity was her principal malady: indeed the had no other complaint but fuch as apparently might be accounted for from this fuppofition. She was ordered to purfue a vegetable diet, and in the fummer to She conformed to thefe directions, drink the waters at Scarborough. became more agile, lefs fleepy, lefs averfe to exercife. She walked up the steps at Scarborough from the fpaw, a tak of no little difficulty to people much lefs encumbered. I urged a continuance of the fame diet: fhe was diffuaded from it by her friends, and died of fat in the twenty-feventh year of her age. She left permiffion with her fifter, to be opened, if it was defired: the cafe was too fingular to be neglected: all the vifcera were perfectly found, but larded with fat beyond apprehenfion. In dividing the external teguments,

It seemed to me that mere obe

we cut through 2 inches of fat. She died fuddenly.

Some inftances of a fimilar nature, in which a vegetable diet has fafely contributed to reduce immoderate corpulency, induces me to think that a prudent trial in the cafe I am treating of (an Angina Pectoris) would be advifeable. Perhaps a reasonable ufe of wine, not a generous one, fhould be here allowed, left the ftrength fhould be diminished too much in proportion; and if the power of abforption fhould by this means fail, we may probably lofe more ground, by the increase of the ferefa colluvies in the cavity of the thorax, than what we gain by fubtracting the fat.

All the means of increafing the thinner fecretions are evidently pointed out as neceffary, from this diffection; and if to thefe we join fmall dofes of chalybeates, or other medicines, and an abftinence from animal food, fo far as the patient's health, fituation, and manner of life will admit of it, we are perhaps rendering all the reasonable affiftance we can, till future difcoveries make us better acquainted with the real caufes of this fingular distemper.

high, enjoyed a good state of health till about the year 1766, when he was feized with violent pains in his knees and feet, and, was tormented with a head-ach, which came on at irregular pe-, riods; thefe pains he fuppofed to be rheumatic, and had recourse to a variety of medicines, and to empirical aid, without finding any alleviation whatever of his complaints. In the month of November of the fame year, he injured his left shoulder by a fall, which occafioned him confiderable pain ; and he was unable to move it for feveral months afterwards.

In November 1768, he flipped down in his fhop, and fancied he had fprained his right thigh; this injury confined him to his bed about a week; and he was afterwards unable to walk without the fupport of a perfon's arm and a crutch-ftick. On the twenty-first of December following, as he was endeavouring to go up stairs to bed, fupported by his wife, he ftruck the toe of his right foot upon the edge of the ftep, and inftantly cried out that his thigh was broke. He was put to bed, and an apothecary being fent for the next morning, who, paying little attention to the injured thigh, attributed the great pain he fuffered to an increase of his rheu medicines accordingly. In this fitumatic complaints, and gave him ation he continued upwards of fician to the London-Hofpital, was fortnight, when Dr. Dickson, phy. called in. Upon his viewing the thigh fo much complained of, he

found it crooked and much shorter than the other, and therefore advifed a furgeon to be sent for.

I faw him the following day,